An arc is a portion or segment of an ellipse, meaning an arc is a non-complete ellipse.
While a pie is a closed shape, an arc is not: it uses only a portion of the line
that defines an ellipse. Because an arc must confirm to the
shape of an ellipse, it is defined as it fits in a rectangle and can be
illustrated as follows:

To support arcs, the Graphics class is equipped with the DrawArc() method that
is provided in four versions whose syntaxes are:

The ellipse that would contain the arc must be drawn in a Rectangle
or a RectangleFrect. You can also define that ellipse by the
coordinates of its inscribed rectangle x, y, and its dimensions width,
height. Besides the borders of the rectangle in which the arc
would fit, an arc must specify its starting angle, startAngle, measured
clockwise from the x-axis its starting point. An arc must also determine its
sweep angle measured clockwise from the startAngle parameter to the end
of the arc. These two value follow the same definitions we reviewed for the Graphics::Pie()
method.